Blow-on contact structure



Dec. 29, 1953 F. J. PoKoRNY 2,664,479

BLow-CN CONTACT STRUCTURE Filed sept. 19, 1951 f a@ INVENTCR.

Fea/vz J. PMae/vy Patented Dec. 29, 1953 BLOW-0N CONTACT STRUCTURE Frank Joseph Pokorny,

Philadelphia, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation Application September 19, 1951, Serial No. 247,266

-My present invention relates to circuit break-l ers, :and more particularly to a contact arrangement for circuit breakers wherein the electromagnetic forces which arise owing to an angular or U-shaped current path which is provided in the circuit breaker around the contacts are utilized to create a blow-on effect; that is, a netl electro-motive force tending to increase the con- 'tact pressure Essentially, my invention contemplates a cir cuit breaker contact having an upper contact element adapted to engage an upper stationary contact element and a lower contact element adapted to engage a lower complementary Contact. This principal contact member is pivota-lly mounted on a movable contact arm in such manner that the lever arm from. the pivot to the upper contact element is shorter than the lever arm from the pivot to the lower contact. element.

The current path forms essentially two right angles, one. on each of the contact elements that the current. path through the main contact is U-shaped. The electromagnetic forces owing to the bend. in the current path tend, as is well known, ordinarily to eiiect separation of con tacts at the bend. However, since the portion of the contact member below the pin is longer than the portion of the contact member above the pin, the blow-off eiect at the lower end of the contact member has a net force not only overcoming the blow-off effect at the upper end of the Contact member, but also increasing Contact pressure at the upper end' of the contact member.

The opening spring for the entire contact assembly is so arranged that it acts through the lower complementary contact on the lower end of the contact member so that the blow-off eiect at this point is compensated for entirely by this opening spring which, therefore, acts also as a contact pressure spring.

By this means, therefore, the electromagnetic forces created by the U-shaped current path pro? duce a blow-on effect at the contact and increase contact pressure.

The primary object of my invention, therefore, is the provision of novel means for utilizing the electromagnetic forces present in a circuit breakerstructure owing to the conformation of the current path therethrough to create additional contact pressure.

Another and complementaryv object of my invention is the utilization of the opening spring for the contact arm as a contact pressure spring for the lower complementary contact so that appropriete contact pressure may be created for this end. of. the contact.. y

9 Claims. (Cl. 20G- 87) The foregoing and many other objects of my invention will become apparent in the following description when taken in connection with the drawing in which:

Figure 1 is a side view partly in cross-section of my novel circuit breaker structure embodying my blow-on contact.

Figure 2 is a front view partly broken away showing my novel circuit breaker in a three pole housing.

As previously pointed out, the essence of theinvention is the blow-on contact arrangement provided for contact l0 yand its contact elements II and I2, achieved by the formation of Contact I0 so that the lever arm from pivot pin I3 of contact I0 to contact element H is shorter than the lever arm from pivot pin i3 of contact It to contact element I2. Thus, blow-on tendency at contact element II is counteracted by a greater similar tendency at contact element I2, which` parallel paths through the bearing 34 of contact 2l to the terminal 35 and also through contacting surface 36 of contact 2l and contacting extension 3'1 of terminal 35 to the terminal 35. From terminalr 35 current iiows to series trip coil 38 and then to lower back connection stud 39.

As above mentioned, the essence of the inven-A tion is the blow-on arrangement of Contact I i', achieved by the right angle arrangement of the current path at contact elements I I and 32 at Ione end and contacts I2 and 22 at the other end' and by the fact that the lever arm from pin I3 to contact element I2 is greater than the lever arm from pin I3 to contact element II; but, for a full understanding of the operation of my invention, the complete circuit breaker structure will now first be described.

The entire circuit breaker structure is supported on an insulating back panel 4G suitably shaped to receive and position the parts and having side extensions 4I providing some interphase protection where the circuit breaker is used as a multi-pole circuit breaker. The main stationary Contact 3l is secured to stud 30 by bolt 43 and to panel 40 byl bolt 44. Intermediate contactl d5- isv also secured to main contact 3i by bolt it. The

arcing contact @E is spaced from stud 35 by insulation 49 and is extended into back arcing horn 55 which in turn is connected through blow-out coil 5I to back connection stud 30.

The movable contact carrying arm 55 is mounted for rotation on pin 55 carried by lower terminal 35 and is rotatable about said pin 56 between the closed position (shown in Fig. l) and the open position.

The operating mechanism (not shown) for moving the arm 55 to closed position and maintaining it there is connected by link 58 to pin I3, which in turn is carried by arm 55. The movable intermediate contact 55 is mounted on U- shaped strap 52 carried by the arm 55.

The movable driving contact element 54 is mounted on the end of arcing contact 65 which in turn is pivotally mounted at 66 at the upper end of arm 55 on sleeve 58 and is in current carrying engagement with arm 55 by reason of flanged end cups and bolt 12.

The head 13 of bolt 12 compresses the spring 14 between it and the base of one of the end cups 1li. The nut 15 at the other end of bolt 12 compresses the spring 15 between it and the base of the other end cup 10, thereby permitting the flanges of the end cups 1I) to exert a strong contact pressure.

The lower lend of the arcing contact 65 is moved toward the stationary arcing contact 5S by compression spring 18 compressed between adjustable nut 19 carried by the front wall 80 of the movable arm 55 and the contact element 64.

4When the trip coil 38 is appropriately energized the armature 85 is attracted from its back-stop 86 to engage the magnet 81, and at that point operates a tripper bar 88 for the operating mechanism so that the link 58 no longer holds the contact arm 55 in the closed position.

Thereafter, the opening spring 20, hereinafter described, will move the contact arm 55 clockwise about the pin 56 to the open position.

The elements shown below the back-stop 85 are conventional Calibrating elements 50 for the pick-up value of the armature and time delay elements 9i and 92 for various operations of the armature. These are now well known and require no further description here.

The terminal 35 carries the spring contact member i535 engaging contact element IUI at the lower end of the movable contact arm 55 providing for a connection between the lower terminal 35 and the movable contact arm 55 so that the intermediate contact 5U and the arcing contact element 54 are provided with an appropriate current path for formation and extinguishment of the arc even after the movable contact arm 55 opens. The contact element Iil replaces the exible shunt or pigtail, which previously has been used for this purpose.

The complementary contact ZI, as previously pointed out, is mounted on pin 34 carried by terminal 35. The opening spring 20 is compressed between the recess III) on the back side of complementary contact 2| and the recess IiI in the lower back panel All. Thus, the opening force on the movable contact arm 55 is transmitted from recess III through compression spring 2li, through recess I Il) of complementary contact 2| to the contact element I2 of the main movable contact i5, through back-stop pin II5 for contact I5, the said pin H5 being iixedly mounted on the arm 55, thereby urging the arm 55 in a clockwise direction around its pivot pin 56. The spring 20 thereby creates appropriate contact pressure between Contact elements 22 and I2.

At the same time, by biasing the contact member 2| in a clockwise direction about its pivot 34, the contact surface 35 which is above the pin 35 is pressed against contact element 31 of Vthe terminal 35 to provide an emcient current carrying path.

The important aspect of my present invention is that when the circuit breaker is closed the contact arrangement is such that a blow-on occurs, thereby utilizing the U-shaped current path from contact element 32 through contact I0 to contact element 22 to assist in maintaining the contact in rm engagement. The movement of the contact arm 55 to closed position brings contact element II of contact member ill against the contact element 32 to rotate the contact Ii) away from its back-stop pin H5 and further compress the spring 20, thereby creating an emcient contact pressure not only between contact elements Il and 32, but also between contact elements I2-l and 22. l

Since the lever .arm from pin I3 to contact element I2 is longer than the lever arm from pin I3 to contact element II, the blow-oir effect which occurs by reason of the angular currentv path at contact element I2, thereby serving to drive the contact member i5 in a counterclockwise direction, overcomes the opposite blow-off effect at contact element II to create additional contact pressure at contact element II and thereby create a net electromagnetic force driving contact elements II and 32 into rmer engagement. n,

The location of the compression spring 20 so that it drives contact 2| toward contact element I2 serves directly to maintain a'iirm contact at the lower end of the contact member Ill. y By this means, therefore, a simplified circuit breaker contact arrangement is provided whereby a net blow-on effect is achieved and the electromagnetic forces which ordinarily tend to separate the contacts or weaken the Contact pressure are instead utilized to increase contact pressure.

In the foregoing I have described my invention solely in connection with specific embodiments thereof. cations of my invention will now be obvious to those skilled in the art, VI prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

l. A blow-on contact structure for electricalV switch gear comprising a movable pivoted contact carrying arm; a contact member 'piv'otally carried by said contact arm; said contact member having a rst contact element and a-second contact element located on opposite sides of the pivotal mounting of said contact member; aV first complementary contact engageable with said iirst contact element; a second complementary contact engageable with said second contact element said nrst contact and said second contact in an electrical series circuit, the first contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary Contact urging it toward said second contact element.

carried by said contact arm; said contact mem'- Since many variations and modiber having a first contactelement and a second contact element located on opposite: sides of the pivotal mounting of said contact member; a first complementary contact engageable with said nrst contact element;` a Asecond complementary contact engageable with said second contact element; the first contact element being closer to the pivotal mounting of said contact member than the second contact element; andr` biasing means for said secondi complementary contact urging it toward said second contact element; the line of contact between said' contact elements and their respective complementary contacts being substantially parallel to the major axis of said contact-member', a single currentpath through each contact element and its complementary contact being at a substantial angle to the current path through the con tact member.

A blow-on contact structure for electrical switch gear comprising a movable pivoted contact' carrying arm; a. contact member` pivotally carried by said contact arm; said contact member having a iirst contact element and a second contact element located on opposite sides of the pivotal mounting of said contact member; a. first complementary contact engageable with said rst contact element;` a second complementary contact engageable with said second ccntact element; the first contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line of contact between said contact elements and theirv respective complementary contacts being substantially parallel to the major axis of said contact member, a single current path through each contact element and its complementary contact being at a substantial angle to the current path through the contact member, and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements.

4. A blow-on Contact structure for electrical switch gear comprising a movable pivoted contact carrying arm; a contact member pivotally carried by said contact arm; said contact member having a nrst contact element and a second Contact element located on opposite sides of the pivotal mounting of said contact member; a first complementary contact engageable with said first contact element; a second complementary contact engageable with said secondA contact element; the rst contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line. of contact between said contact elements jand their respective complementary contacts being substantially parallel to the major axis of said contact member, the current path through each contact element and its complementary contact being at a substantial angle to the current path through the contact member, the current path through said contact elements and said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements.

5. A blow-on contact structure for electrical switch gear comprising a movable pivoted con tact carrying arm; a contact member pivotally carried by said contact arm; said contact member having' a first contact element. and a second-1 con-tact urging it toward saidl second contact'- element; the line of contact between said contact elements and their respective complementary contacts being substantially' parallel to the major axis of said contact member, the current path through each contact element and its com plementary contact being at a substantial angle to the current path through the contactV member, the current path through said contact elements and said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contacty elemen-ts, the greater distance of the second contact element from the pivotal mounting translating said electromagnetic opening force at that' Contact into a mechanical closing force at the first contact element exceeding the electromagnetic opening force at said rst contact element.

6. A blow-on contact structure for electrical switch gear comprising a movable pivoted contact carrying arm; a contact member pivotally carried by said Contact arm; said contact member having a first contact element and a second contact element located on opposite sides of the pivotal mounting of said contact member; a first complementary contact engageable with said first contact element; a second complementary Contact engageable with said second contact element; the nrst contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line of Contact between said contact elements and their respective complementary contacts being substantially parallel to the major axis of said contact member, the current path through each contact element and its complementary contact being at a substantial angle to the current path through the contact member, the current path through said contact elements and' said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements, the greater distance of the second contact element from the pivotal mounting translating said electromagnetic opening force at that contact into a mechanical closing force .at the rst contact element exceeding the electromagnetic opening force at said first contact element and driving said rst contact element into firmly closed position.

'LA blow-on contact structure for electrical switch gear comprising a movable pivoted contact carrying arm; a contact member pivotally carried by said contact arm; said contact member having a first contact element and a second contact element located on opposite sides of the pivotal mounting of said contact member; a rst complementary contact engageable with said rst contact element; a second complementary contact engageable with said second contact element; the rst contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line of contact between said contact elements and their respective complementary contacts 'being substantially parallel to the major axis of said contact member, the current path through each contact element and its complementary contact being at a substantial angle to the current path through the contact member, the current path through said contact elements and said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements, the greater distance of the second contact element from the pivotal mounting translating said electromagnetic opening force at that contact into a. mechanical closing force at the iirst contact element exceeding the electromagnetic opening force at said first contact element and driving said rst contact element into firmly closed position; the biasing means at the second complementary contact having a component of force in the Asame direction as the electromagnetic opening force at said second contact element and exceeding the electromagnetic opening force at said second contact element.

8. A blow-on contact structure for electrical switch gear comprising a, movable pivotedcontact carrying arm; a contact member pivotally carried by said contact arm; said contact member having a rst contact element and a second contact element located on opposite sides of the pivotal mounting of said contact member; a first complementary contact engageable with said rst contact element; a second complementary contact engageable with said second contact element; the irst contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line of contact between said contact elements and their respective complementary contacts being substantially parallel to the major axis of said Contact member, the current path through each contact element and its complementary contact being at a substantial angle to the current path through the contact member, the current path through said contact elements and said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements, the greater distance of the second contact element from the pivotal mounting translating said electromagetic opening force at that contact into a mechanical closing force at the first contact element exceeding the electromagnetic opening force at said rst contact element and driving said iirst contact element into firmly closed position; the biasing means at the second complementarycontact having a component of force in the same direction as the electromagnetic opening force at said second contact element and ex` ceeding the electromagnetic opening force at said second contact element, said biasing means acting through said second contact element and said contact member also to drive said first contact element into firm contact engagement with said first complementary contact.

9. A blow-on contact structure for electrical switch gear comprising a movable pivoted contact carrying arm; a contact member pivotally carried by said contact arm; said contact member having a rst contact element and a second contact element located on opposite sides of the pivotal mounting of said contact member; a nrst complementary contact engageable with said rst contact element; a second complementary contact engageable with said second contact element; the'nrst contact element being closer to the pivotal mounting of said contact member than the second contact element; and biasing means for said second complementary contact urging it toward said second contact element; the line of contact between said contact elements and their respective complementary contacts being substantially parallel to the major axis of said contact member, the current path through cach contact element and its complementary contact being at a substantial angle to the current path through the contact member, the current path hrough said contact elements and said contact member being U-shaped and creating, when the circuit breaker is closed, electromagnetic opening forces at said contact elements, the greater distance of the second contact element from the pivotal mounting translating said electromagnetic opening force at that contact into a mechanical closing force at the rst contact element exceeding the electromagnetic opening force at said first contact element and driving said first contact element into firmly closed position; the biasing means at the second complementary contact having a component of force in the same direction as the electromagnetic opening force at said second contact element and exseeding the electromagnetic opening force at said second contact element, said biasing means acting through said second contact element and said contact member also to drive said rst contact element into firm contact engagement with said iirst complementary Contact, said biasing means acting also through said second complementary contact and said second contact element and the Contact member as an opening spring for the contact arm.

FRANK JOSEPH POKORNY.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,283,748 Mathieu May 19, 1942 V2,329,003 Seaman Sept. 7, 1943 

